Layup schedual for custom hardtop

[mcgyver]

I've decided to build my own hardtop this fall 5' 3" wide by 6.5' long, 1.5" radiused lip all the way around (will add strength to the top). I'm building a female mold with a slight 1" curve to the top. The corners will be radiused with "clay putty"? When the negative is perfect i will spray with PVA then spray or roll? white gelcoat, let it set and then proceed with 1.5 oz csm then?..... 24 oz roving? followed by how many layers of csm? topped with 3/4 oz cloth for the finished inside look? I'm at a loss for the layup schedual I should use, I don't want too little but too much will impact the weight which i want to keep down...... ideas? thanks BTW poly resin

 

[oops!]

Re: Layup schedual for custom hardtop

hi bud.

spray the gellcoat in the mold.....rolling will give you an uneven thickness coating. this will cause crazing if you dont get it right. spray is even. use unwaxed gell

after that is cured....an hour or so.....then lay 1.5 csm....1708....1.5 ...1708... then 1.5 then the finishing cloth......wait till the heat has gone out of the cure....and gell the glass.

for the deep corners that the 1708 will not conform to.....add pb between the layers of csm and 1708 till its flat enough for the larger cloth.
i would not use the roving...simply because it will only bend one direction and the possibility of resin rich layers is greatly increased with a larger weave.

if you use the pb...wait till the heat has gone out of the cure before you add the next layer of glass.

you dont want to cook the resin.

with the mold being as intricate as it needs to be for a top.....make sure you dont have any hang up spots in the mold where the part will not come out of.

 

[oops!]

Re: Layup schedual for custom hardtop

remember.....the weight of the top will come from the resin.....use as little as you can......mix colder and really work the resin with your roller till you are fully saturated.
you are looking for a 40 % resin to a 60% glass if you can....if you can find a way to vac bag it......do it. even a good hand pump into a run off jar will work.

 

[mcgyver]

Re: Layup schedual for custom hardtop

Thanks oops....... how thick do you think that will get the final? 1/4"?
Doug

 

[oops!]

Re: Layup schedual for custom hardtop

just over depending on the resin.......the less resin the thinner the glass......but thinner does not necessarily mean weaker.

you will be able to walk around on the top with out a problem.......if you wish to stiffen it.....add cross beams of some type in the glass......i used plastic pipe that is scuffed.

look at the hull thread.......when i built the swim grid for it.

 

[mcgyver]

Re: Layup schedual for custom hardtop

I'm having trouble locating a putty that I am sure can be used with poly resin. i'll be spraying with pva before the gelcoat and want to use clay or modelling putty to form the rounded fillets. Can anyone chime in as to what to use? thanks

 

[Yacht Dr.]

Re: Layup schedual for custom hardtop

Most non-structural parts are choppered ..

CSM is all you need with GP resin .. and secure points should be reinforced ..

1/4" is a bit much for you application IMO ..

A 2 part Clay mold is good if your doing a One off part.

YD.

 

[proshadetree]

Re: Layup schedual for custom hardtop

There is also the choice for mold on or mold off method. I have used both but on much smaller parts. Mold on is what you sound like you are building. This method is normally used for many parts or mass production. For a one off part you can also build the top on a flat surface and then when its finished gel it. Like I said it works great for smaller parts like roll pans and tail light covers. I can not attest to larger items Opps and YD would be the experts here.

 

[oops!]

Re: Layup schedual for custom hardtop

any modeling clay or putty......just pva it......the pva will act as a barrier

 

[mcgyver]

Re: Layup schedual for custom hardtop

Thanks everyone....